1. Field of the Invention
This invention relates to antimicrobial compositions, and, more particularly, to a defined blend of a 1,2-diol and phenoxyethanol, optionally with a co-biocide, which compositions show broad activity against bacteria, fungi and mold spores.
2. Description of the Prior Art
Personal care products come in many different forms. They include creams, lotions, pastes, liquids, aerosols, shampoos, gels, wipes, bars, sticks, powders and granules any or all of which are intended for topical application to the skin including the scalp and the mucosa including the lips.
The products are generally designed to have a substantial shelf life. The products need to be manufactured at one site, transported possibly over a considerable distance to a depot or other storage facility prior to further transport to a point of sale. The product may then spend considerable time on a retailer's shelf prior to purchase and further storage by the user whether for individual use or use in, for example, a hotel, workplace, institution or the like. All of such storage will take place under uncontrolled conditions including considerable variation in temperature.
In order to keep bacterial and fungal growth in such products at an acceptable level it is conventional practice for the products to contain a preservative. Many preservatives are available. The appropriate preservative has to be selected with regard to its efficacy and its acceptability to contact with human or animal skin. With regard to its acceptability there are in many countries laws and regulations governing the maximum permitted content of preservative in products intended for human use due to their possible toxic or otherwise harmful effect.
The need to control microbiological growth in personal care products is known to be particularly acute in water based products such as non-ionic oil-in-water emulsions and in pre-impregnated wipes such as baby wipes.
For example, U.S. Pat. No. 6,607,738 described a preservative system of iodopropynyl butyl carbamate (IPBC) and phenoxyethanol (PE) in a weight ratio of 1:90 to 1:400 for use in personal care products.
U.S. Pat. No. 5,516,510 also disclosed deodorizing active ingredients to reduce the unpleasant odor caused by microorganisms which comprised a glycerin monoalkyl ether in combination with an astringent and/or a naturally occurring deodorant.
EP 1206933 described a preservative composition of caprylyl glycol (1,2-octanediol) and iodopropynyl butyl carbamate in a weight ratio of 0.1 to 500.
U.S. Pat. No. 5,733,362 was directed to a bacterial composition of 2-methyl-4,5-trimethylene-4-isothiazoline-3-on; 3-iodo-2-propynyl butyl carbamate and 2-phenoxyethanol.
EP 1238651 described that the activity of preservative mixtures of iodopropynyl butyl carbamate and phenoxyethanol, in a weight ratio of 1:90 to 1:200, preferably 1:100, can be potentiated by adding caprylyl glycol thereto, in a weight ratio of the latter to the mixture of 0.1 to 500, preferably 1:55. Thus the formulation of caprylyl glycol, iodopropynyl butyl carbamate and phenoxyethanol had weight ratios of each of 55:1:100 to 200:1:400, respectively. The personal care formulations contained 0.1-30% caprylyl glycol, preferably 0.5%; with 0.001-1% IPBC, preferably 0.001-0.01%; and with phenoxyethanol of 0.1-3%, preferably 0.5-1%.
JP Application No. 11045504 described an antiseptic microbicide and compositions thereof which contained a 1,2-alkane diol. These compositions effectively reduced the required dosage of conventional antiseptic microbicides such as paraben, benzoic acid and the like. The 1,2-alkane diol therein could be blended with a photosensitizer, benzoic acid or its salt, phenoxyethanol or 4-isopropyl-3-methylphenol. However, there was no disclosure of suitable blends of 1,2-alkane diol and phenoxyethanol at predetermined weight ratios and HLB values, which could deliver water insoluble biocides such as IPBC into aqueous personal care systems at a relatively high concentration of such biocides.
These and other prior art references in this field were concerned with the problem that many are antibacterials such as IPBC have limited aqueous solubility in personal care systems; particularly at the high concentrations necessary for effective antimicrobial activity. Thus, at very low concentrations they remain in solution but do not contribute as much activity as desired for these products.
Accordingly, it is desired to provide a blend of 1,2-diol and phenoxyethanol at a predetermined ratio and HLB value which can deliver water insoluble biocides into an aqueous personal care system at relatively high concentrations thereby providing more effective preservative activity in such systems.